Semiconductor light emitting element and method of making the same

ABSTRACT

A semiconductor light-emitting element  10  includes a silicon single crystal substrate  20  having a first and a second surfaces  20   a   , 20   b  in head-tail relationship with each other, a GaN-based semiconductor laminate  40  formed on a selected region of the first surface with a predetermined conductive intermediate layer  25  interposed therebetween, a first electrode layer  51  having a portion in contact with an uppermost layer of the GaN-based semiconductor laminate  40  and insulated from the monocrystal silicon substrate, and a second electrode layer  52  formed on a suitable portion of the monocrystal silicon substrate. The monocrystal silicon substrate  20  is formed with a light guide  30  for directing light emitted from the GaN-based semiconductor laminate  40  toward the second surface  20   b.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a semiconductor GaN-based lightemitting element containing gallium nitride and to a method of makingthe same.

[0003] 2. Description of the Related Art

[0004] A semiconductor light-emitting element (a blue-colorlight-emitting diode) for blue-color light emission has been developedand put to practical use. It has a sapphire substrate on which acompound semiconductor crystal containing gallium nitride (GaN) isepitaxially grown by vapor-phase growth of an organic metal compound.Since sapphire differs only slightly in lattice constant from aGaN-based semiconductor crystal, it provides a suitable surface forepitaxially growing a GaN-based compound semiconductor layer whilesucceeding the crystal orientation of the sapphire.

[0005] However, since sapphire is expensive and has poor processability,a conventional diode for blue-color light emission fabricated with useof such a substrate is inevitably expensive.

[0006] On the other hand, JP-A-2000-31534 for example discloses atechnique utilizing a silicon single crystal substrate as an inexpensiveand readily processible substrate for making a blue-color light-emittingdiode. According to this technique, a monocrystal silicon substrate issurface-treated with hydrogen and then formed with a titanium nitridelayer as an intermediate layer for growth of a GaN-based semiconductor.Such hydrogen surface treatment makes hydrogen joined to dangling bondson the surface of the silicon substrate, which prevents formation oftitanium silicide which is an amorphous layer. Further, since titaniumnitride has a cubic crystal structure similarly to silicon, titaniumnitride can be appropriately grown on the silicon substrate whilesucceeding the crystal orientation of silicon. Further, by properlysetting the thickness of the TiN layer, the GaN-based compoundsemiconductor layers subsequently formed thereon also succeed thecrystal orientation of silicon.

[0007] In place of forming an intermediate layer of TiN as describedabove, the above document also proposes another method which utilizes anintermediate layer made of AlN/AlCaN for forming a blue-light-emittingdiode by epitaxial growth of a GaN-based semiconductor on a monocrystalsilicon substrate.

[0008] However, since silicon is a light-absorptive material as isgenerally known, the blue-color light-emitting diode disclosed in theabove document still has room for improvement in light-emittingefficiency.

[0009] To improve light-emitting efficiency, JP-A-5-13816 for exampleproposes a technique which takes advantage of transparency of a sapphiresubstrate for emitting light from the sapphire substrate.

[0010] However, since sapphire is expensive and has a poorprocessability as described above, a blue-color light-emitting diodefabricated with use of a sapphire substrate is still expensive. Further,it is desirable to make the chip as small as possible in view of thehigh cost of the substrate while also increasing the current densitypassing through the activation layer. Then, some practical and usefulway must be sought for properly mounting such a compact chip on a mothersubstrate or frame while maintaining the light-emitting efficiency.

SUMMARY OF THE INVENTION

[0011] The present invention has been proposed under the circumstancesdescribed above. It is, therefore, an object of the present invention toprovide a semiconductor light-emitting element which is less costly butyet provides enhanced light-emitting efficiency.

[0012] It is another object of the present invention to provide asemiconductor light-emitting element which can be easily mounted on acarrier while providing good light-emitting efficiency.

[0013] To fulfill the above-mentioned objects, the present inventionemploys the following technical measures.

[0014] A semiconductor light-emitting element according to a firstaspect of the present invention comprises a silicon single crystalsubstrate having a first and a second surfaces in head-tail relationshipwith each other, a GaN-based semiconductor laminate formed on a selectedregion of the first surface with a predetermined conductive intermediatelayer interposed therebetween, a first electrode layer having a portionin contact with an uppermost layer of the GaN-based semiconductorlaminate and insulated from the monocrystal silicon substrate, and asecond electrode layer formed on a suitable portion of the monocrystalsilicon substrate. The monocrystal silicon substrate is formed with alight guide for directing light emitted from the GaN-based semiconductorlaminate toward the second surface.

[0015] According to a preferred embodiment, the light guide comprises ahole penetrating the monocrystal silicon substrate thicknesswise, andthe GaN-based semiconductor laminate includes a lowermost layer whosesurface includes a portion substantially exposed to the second surface.

[0016] In this case, the hole may be preferably filled with translucentresin. Further, the resin may preferably contain a fluorescent or lightscattering material.

[0017] In the preferred embodiment, the hole flares to have increasingdiameter toward the second surface. Alternatively, the hole may beparabolic to have increasing diameter toward the second surface.

[0018] In the preferred embodiment, the uppermost layer of the GaN-basedsemiconductor laminate is covered with a insulating layer excepting apredetermined center region contacting the first electrode layer.

[0019] In the preferred embodiment, the center region has a diametersmaller than that of the hole formed with the monocrystal siliconsubstrate.

[0020] In the preferred embodiment, the selected region is provided in adepression of the first surface. The depression may be preferably filledwith a protective member. Further, the protective member may bepreferably heat-conductive.

[0021] According to another preferred embodiment, the GaN-basedsemiconductor laminate has a portion positioned offset thicknesswiserelative to the other portion.

[0022] According to a further preferred embodiment, the first surface ofthe monocrystal silicon substrate is formed with another electronicelement.

[0023] Preferably, the first and the second electrode layers may bearranged on the first surface side of the monocrystal silicon substrate.

[0024] A second aspect of the present invention provides a mountingstructure of a semiconductor light-emitting element which ischaracterized that the semiconductor light-emitting element according tothe first aspect is mounted on a carrier with the first surface directeddownward.

[0025] A third aspect of the present invention provides a method ofmanufacturing a semiconductor light-emitting element, which ischaracterized by the following steps.

[0026] (a) A step of forming a GaN-based semiconductor laminate on aselected region of a first surface of a monocrystal silicon substratewith a predetermined conductive intermediate layer interposedtherebetween. The monocrystal silicon substrate also having a secondsurface in head-tail relationship with the first surface.

[0027] (b) A step of forming a first electrode layer and a secondelectrode layer. The first electrode layer has a portion in contact withan uppermost layer of the GaN-based semiconductor laminate and isinsulated from the monocrystal silicon substrate. The second electrodelayer is formed on a suitable portion of the monocrystal siliconsubstrate.

[0028] (c) A step of forming a light guide in the monocrystal siliconsubstrate for directing light emitted from the GaN-based semiconductorlaminate toward the second surface.

[0029] A fourth aspect of the present invention provides a semiconductorlight-emitting element which comprises a monocrystal silicon substratehaving a first and a second surfaces in head-tail relationship with eachother, and a light-emitting diode chip mounted on a selected region ofthe first surface. The monocrystal silicon substrate is formed with alight guide for directing light emitted from the light-emitting diodechip toward the second surface.

[0030] According to a preferred embodiment, the light-emitting diodechip is a blue-color light-emitting diode chip formed by growing aGaN-based semiconductor laminate on a sapphire substrate.

[0031] In this case, the blue-color light-emitting diode chip may bemounted on the selected region with the sapphire substrate directeddownward. Alternatively, the blue-color light-emitting diode chip may bemounted on the selected region with the sapphire substrate directedupward.

[0032] In the preferred embodiment, the light guide comprises a holepenetrating the monocrystal silicon substrate thicknesswise with aportion of the light-emitting diode chip substantially exposed to thesecond surface side.

[0033] In the preferred embodiment, the hole may be preferably filledwith translucent resin. Further, the resin may preferably contain afluorescent or light scattering material.

[0034] In the preferred embodiment, the hole flares to have increasingdiameter toward the second surface. Alternatively, the hole may beparabolic to have increasing diameter toward the second surface.

[0035] In the preferred embodiment, the selected region is provided in adepression of the first surface. In this case, the depression may bepreferably filled with a protective member.

[0036] In another preferred embodiment, the first surface of themonocrystal silicon substrate is formed with another electronic element.

[0037] Preferably, the first surface of the monocrystal siliconsubstrate may be provided with a first electrode layer connected to anelectrode of the blue-color light-emitting diode chip, and a secondelectrode layer connected to another electrode of the blue-colorlight-emitting diode chip.

[0038] A fifth aspect of the present invention provides amountingstructure of a semiconductor light-emitting element, wherein thesemiconductor light-emitting element according to the fourth aspect ofthe present invention is mounted on a carrier with the first surfacefacing downward.

[0039] Other features and advantages of the present invention willbecome clearer from the detailed description of the preferredembodiments given below with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0040]FIG. 1A is a vertical sectional view a semiconductorlight-emitting element according to showing a first embodiment of thepresent invention, whereas FIG. 1B is a vertical sectional view showinga semiconductor light-emitting element according to a modification ofthe first embodiment of the present invention;

[0041]FIG. 2 is an enlarged sectional view of a principal part of thesemiconductor light-emitting element shown in FIG. 1A;

[0042] FIGS. 3A-3E show an example of method of making the semiconductorlight-emitting element shown in FIG. 1A;

[0043]FIG. 4 shows the semiconductor light-emitting element of FIG. 1Ain a mounted condition;

[0044]FIG. 5 is a sectional view showing a principal part of asemiconductor light-emitting element according to a second embodiment ofthe present invention;

[0045]FIG. 6 is a sectional view showing a principal part of asemiconductor light-emitting element according to a third embodiment ofthe present invention.

[0046]FIG. 7 is a sectional view showing a principal part of asemiconductor light-emitting element according to a fourth embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0047] Preferred embodiments of the present invention will be describedbelow in detail with reference to the accompanying drawings. FIG. 1A isa view of a semiconductor light-emitting element 10, in verticalsection, according to a first embodiment of the present invention, FIG.1B is a view of a modification of the first embodiment, in verticalsection, FIG. 2 is an enlarged view showing a principal part of FIG. 1A,and FIGS. 3A-3E show an example of process for making the semiconductorlight-emitting element shown in FIG. 1A.

[0048] As shown in FIGS. 1A and 2, the semiconductor light-emittingelement 10 includes a monocrystal silicon substrate 20 of apredetermined thickness having an upper or first surface 20A and a loweror second surface 20B. The monocrystal silicon substrate 20 isrectanglar in plan view for example. The upper surface of themonocrystal silicon substrate 20 has a selected center region formedwith a depression 21 of a predetermined depth. The depression 21 iscircular in plan view for example.

[0049] The monocrystal silicon substrate 20 is formed with athorough-hole 31 extending thicknesswise from the bottom of thedepression 21 to the second surface 20 b. The through-hole 31 preferablyflares to have increasing diameter toward the second surface 20 b.

[0050] The depression 21 is provided with a GaN-based semiconductorlaminate 40 riding on a peripheral mouth portion 31 a of the hole 31.More specifically, as clearly shown in FIG. 2, the GaN-basedsemiconductor laminate 40 includes for example an N-type semiconductorlayer 41 (GaN layer or AlGaN layer), an activation layer 42 (InGaNlayer), and a P-type semiconductor layer 43 (GaN layer of AlGaN layer).These layers are successively formed by epitaxial growth. To realizeappropriate growth of the GaN-based semiconductor laminate 40 on themonocrystal silicon substrate 20, an intermediate layer 25 of e.g.titanium nitride (TiN) is first formed on the monocrystal siliconsubstrate 20 before the growth of and then the GaN-based semiconductorlaminate 40. A method of forming the GaN-based semiconductor laminate 40will be described later with reference to FIGS. 3A-3E.

[0051] The uppermost layer of the GaN-based semiconductor laminate 40has a surface held in contact with a part of a first electrode layer 51.The first electrode layer 51 is insulated from the monocrystal siliconsubstrate 20. More specifically, the first surface 20 a of themonocrystal silicon substrate 20 is formed with an insulating layer 61of e.g. SiO2 by vacuum spattering or vapor deposition optionallycombined with etching. The insulating layer covers the uppermost layerof the GaN-based semiconductor laminate 40 other than a predeterminedcenter region while also covering a region from the depression 21 to thefirst surface 20 a where the first electrode layer 51 extends. The firstelectrode layer 51 is formed by vacuum spattering or vapor deposition ofan Au- or Ag-based conductive metal optionally combined with etching. Inthe illustrated embodiment, first electrode layer 51 has one endcontacting the upper surface of the GaN-based semiconductor laminate 40at the inside of the depression 21, whereas the other end is positionedat a suitable portion over the first surface 20 a of the monocrystalsilicon substrate 20. The insulating layer 61 has a mouth 61 a, which isdiamatically smaller than the mouth 31 a of the hole 31 on the firstsurface 20 a of the monocrystal silicon substrate 20 for exposing theupper surface of the semiconductor laminate 40. The first surface 20 aof the monocrystal silicon substrate 20 also has a suitably selectedportion formed with a second electrode layer 52 electrically connectedto the monocrystal silicon substrate 20. The second electrode layer 52may be formed in the same manner as the first electrode layer 51.

[0052] The depression 21 is filled with a protective member 62 of e.g.epoxy resin for partially burying the first electrode layer 51. Theprotective member 62 preferably contains a good heat-conductive materialsuch as a silicon for adjusting heat dissipation.

[0053] The hole 31 is preferably filled with a translucent resin 32 suchas epoxy resin. The epoxy resin serves as a light guide 30 for guidinglight emitted from the GaN-based semiconductor laminate 40 toward fromthe second surface 20 b side while also serving as a protective memberfor the semiconductor laminate 40. The epoxy resin may be contain alight scattering material such as fluorescent or metalic particles.

[0054] With the structure described above, the P-type semiconductorlayer 43 of the GaN-based semiconductor laminate 40 is connected to thefirst electrode layer 51, whereas the N-type semiconductor layer 41 isconnected to the second electrode layer 52 via the monocrystal siliconsubstrate 20. Consequently, voltage application across the electrodelayers 51 and 52 causes the activator 42 of the GaN-based semiconductorlaminate 40 to emit blue-light. The light can be efficiently let outbeyond the second surface 20 b of the monocrystal silicon substrate 20via the light guide 30. As described above, when the light guide 30(epoxy resin 32) contains a fluorescent or light scattering material,light can be adjusted emitted efficiently from the entire mouth of thelight guide 30 beyond the second surface 20 while also providing apossibility for color adjustment. Further, in the illustratedembodiment, the exposed portion of the GaN-based semiconductor laminate40 at the first surface 20 a side is completely covered with a metalelectrode layer (the first electrode layer 51). Consequently, the metalelectrode layer serves as a reflector for efficiently reflecting light,traveling from the activation layer 42 upward in FIG. 1A, toward thelight guide 30, which also results in significant improvement inlight-emitting efficiency. Further, the mouth 61 a of the insulatinglayer 61 covering the GaN-based semiconductor laminate 40 at the firstsurface 20 a has is diametrically smaller than the light guide 30.Consequently, the activation layer 42 can emit light primarily from theselected center region. Thus, the light-emitting portion can beprevented from being shaded behind the edge 31 a of the hole 31 of themonocrystal silicon substrate 20, which also contributes to improvementof light-emitting efficiency.

[0055] In addition, the substrate of the semiconductor light-emittingelement 10 is made of monocrystal silicon. Consequently, as shown inFIG. 1B, wafer process maybe performed on the first surface 20 a of thesubstrate 20 to form another element or a set of elements 90 such as acurrent regulating drive circuit or a logic circuit as a part of anIC-built-in semiconductor light-emitting element, or to form a discreteelement such as a diode, or sensor or the like.

[0056]FIG. 4 shows an example of mounting structure wherein thesemiconductor light-emitting element 10 having the above-describedarrangement is mounted on a carrier such as a mother board 5. Since thefirst electrode layer 51 and the second electrode layer 52 are formed onthe first surface 20 a of the monocrystal silicon substrate 20, thesemiconductor light-emitting element 10 can be mounted in face-downrelation onto the mother substrate 5. In such a mounting structure,light emitted from the GaN-based semiconductor laminate 40advantageously goes out upward via the light guide 30.

[0057] Next, reference is made to FIGS. 3A-3E for describing an exampleof process of making the semiconductor light-emitting element 10 havingthe above-described structure.

[0058] As shown in FIG. 3A, a monocrystal silicon substrate 20 isprepared. The monocrystal silicon substrate 20 has a thickness of200-400 μm and includes a first and a second surfaces 20 a, 20 b inhead-tail relationship. The figure shows a devided region only for anindividual semiconductor light-emitting element which is rectangular intop view. In actual production, use may be made of a wafer whichcorresponds to a plurality of such regions arranged vertically andhorizontally. The first surface 20 a has a depression 21 formed byetching for example. The depression 21 is circular for example in topview.

[0059] The depression 21 on the first surface 20 a of the Monocrystalsilicon substrate 20 is formed with a GaN-based semiconductor laminate40. To form properly such a semiconductor laminate 40, the monocrystalsilicon substrate 20 is hydrogen-terminated follower by forming anintermediate layer 25 of titanium nitride (TiN) by plasma spattering forexample. Subsequently, the GaN-based semiconductor laminate 40 is formedon the intermediate layer by epitaxial growth. More specifically, theGaN-based semiconductor laminate 40 is formed by successive epitaxialgrowth of an N-type semiconductor layer 41 (GaN layer or AlGaN layer),an activation layer 42 (InGaN layer), and a P-type semiconductor layer43 (GaN layer or AlGaN layer). To limit the area of the GaN-basedsemiconductor laminate 40 to the region of the depression 21, thesemiconductor laminate 40 may be firstly grown on the whole area of thefirst surface 20 a of the monocrystal silicon substrate 20, followed byetching away an excessive portion. Alternatively, the semiconductorlaminate 40 may be formed by selective epitaxial growth for limittingthe growth region. When the monocrystal silicon substrate isHydrogen-terminated and then formed with a TiN intermediate layer, aGaN-based semiconductor laminate can be properly grown thereon, aspreviously mentioned at the beginning of this specification.

[0060] Next, as shown in FIG. 3C, a predetermined portion of the firstsurface 20 a of the monocrystal silicon substrate 20 is formed with aninsulating layer 61 of a silicon oxide layer (SiO2) for example as byvapor deposition, spattering or the like. The insulating layer 61 coversthe depression 21 except for the central portion of the upper surface ofthe GaN-based semiconductor laminate 40 and extends to a suitableportion of the first surface 20 a. The coverage area of the insulatinglayer 61 may be selected by etching.

[0061] Next, as shown in FIG. 3D, a first and a second electrode layers51 and 52 are formed. As described above, the first electrode layer 51is formed in contact with the exposed portion of the upper surface ofthe GaN-based semiconductor laminate 40 and extends to a suitableposition on the first surface 20 a. The second electrode layer 52 isdirectly formed on an appropriate portion of the first surface 20 a ofthe monocrystal silicon substrate 20. The first and second electrodelayers 51, 52 are formed by vapor deposition or spattering, and theircoverage areas are selected by etching. The electrode layers 51, 52 aremade of an Au- or Ag-based metal material for example.

[0062] Next, as shown in FIG. 3E, the monocrystal silicon substrate 20is formed with a hole 31 extending from the second surface 20 b topartially expose the bottom surface of the GaN-based semiconductorlaminate 40. The hole 31 may be formed by etching for example.

[0063] Next, the depression 21 of the first surface 20 a is filled witha protective member 62, and the hole 31 is filled with translucent resin32 such as epoxy resin. Then, the wafer is divided into unit elementsfor providing the semiconductor light-emitting elements 10 each havingthe structure shown in FIG. 1A.

[0064]FIG. 5 is a sectional view showing a principal part of asemiconductor light-emitting element 10 according to a second embodimentof the present invention. This embodiment differs from the embodimentshown in FIG. 1A in the following respects. A GaN-based semiconductorlaminate 40 includes a central region positioned offset toward a firstsurface 20 a of a monocrystal silicon substrate 20 relative to aperipheral region. A hole 31 formed in the monocrystal silicon substrate20 is parabolic with its diameter increasing toward the second surface20 b. Further, the hole 31 has an inner surface provided with areflector 33 formed by vapor deposition of Ag or A1 for example. Thestructure is otherwise the same as in the embodiment shown in FIG. 1A,and is not further described.

[0065] Since the GaN-based semiconductor laminate 40 is partially offsetas described above, the surface of the semiconductor laminate 40 isbent. Since the GaN-based semiconductor laminate 40 has a reflectiveindex of no less than 2, light emitted from the activation layer 42encounters difficulty in going out. However, the bent surface of thesemiconductor layer 40 increases the possibility that the lighttraveling within the semiconductor laminate 40 strikes into the surfaceat an angle smaller than the critical reflection angle, which assiststhe light to go out. This contributes to improvement in thelight-emitting efficiency of the semiconductor light-emitting element10.

[0066] Further, since the inner surface of hole 31 is parabolic innersurface as described above with the reflector 33 formed thereon, lightcan be efficiently emitted outside. It is easily understood that thesemiconductor light-emitting element 10 according to this embodiment canbe fabricated in the same manner as described above with reference toFIGS. 3A-3E.

[0067]FIG. 6 is a sectional view showing a semiconductor light-emittingelement 10 according to a third embodiment of the present invention. Thesemiconductor light-emitting element 10 has a monocrystal siliconsubstrate 20 including a first and a second surfaces 20 a, 20 b. Thefirst surface 20 a is provided with a blue-color light-emitting diodechip 70 fabricated in a conventional manner. Light emitted from theblue-color light-emitting diode chip 70 goes out from the second surface20 b of the substrate 20 via a light guide 30 penetrating themonocrystal silicon substrate 20.

[0068] The blue-color light-emitting diode chip 70 fabricated in theconventional manner has a sapphire substrate 71 including an uppersurface successively formed with an N-type semiconductor layer 72 (GaNlayer or AlGaN layer), an activation layer 73 (InGaN layer), and aP-type semiconductor layer 74 (GaN layer or AlGaN layer). The N-typesemiconductor layer 72 has an exposed portion formed with an N-sideelectrode 52, whereas the P-type semiconductor layer 74 includes asurface formed with a P-side electrode 51. In this embodiment, the chipis mounted on a depression 21 formed on the first surface 20 a with thesapphire substrate 71 positioned below. Each of the N-side electrode 52and the P-side electrode 51 is connected, by wire bonding, to acorresponding wiring pattern 80 arranged on the first surface 20 a.Wiring patterns 80 corresponding to the N-side electrode 52 and theP-side electrode 54 extend to suitable portions on the first surface 20a where bumps 63 are formed. Each wiring pattern 80 has a lower surfaceformed with an insulating layer 61 made of e.g. silicon oxide film forinsulation from the monocrystal silicon substrate 20.

[0069] As in the first embodiment, the hole 31 formed in the monocrystalsilicon substrate 20 is preferably filled with translucent resin 32 suchas epoxy resin. The depression 21 on the first surface 20 a is alsofilled with a protective member 62 such as epoxy resin to protect thechip 70 and the bonding wires 75.

[0070] In the structure described above, light emitted from theactivation layer 73 of the light-emitting diode chip 70 travels via thetransparent sapphire substrate 71 and the light guide 30 to go outefficiently from the second surface 20 b. The P-side electrode 51 whichis a full-surface electrode functions as a reflector. Thus, lightemitted from the activation layer 73 upward in FIG. 6 is reflectedtoward the light guide 30 to go out from the second surface 20 b of thesubstrate 20 efficiently without being wasted.

[0071] In this embodiment, similarly to the first embodiment, themonocrystal silicon substrate 20 may be formed integrally with a currentregulating drive circuit or a logic circuit by wafer process. Thesemiconductor light-emitting element may be mounted on a carrier such asa mother substrate 5 with the first surface 20 a of the substrate 20directed down.

[0072]FIG. 7 is a sectional view showing a semiconductor light-emittingelement 10 according to a fourth embodiment of the present invention.This embodiment, as in the embodiment shown in FIG. 6, utilizes ablue-color light-emitting diode chip 70 fabricated in a conventionalmanner. However, the chip is mounted on a sapphire substrate 71positioned above. In this case, an N-side electrode 52 and a P-sideelectrode 51 are adjusted in height, and each of the electrodes 51, 52is connected directly to a respective wiring pattern 80 via ananisotropic conductive layer or a conductive adhesive. The structure isotherwise the same as in the embodiment shown in FIG. 6, and is notfurther described. It may be easily understood that this embodimentenjoys the same benefits as the embodiment shown in FIG. 6. In addition,in this embodiment, when the surface of the sapphire substrate 71 isformed with a metal reflector (not shown), light traveling from theactivation layer 73 upward in the figure is reflected toward the lightguide 30, which enhances light-emitting efficiency of the semiconductorlight-emitting element 10.

[0073] The present invention is not limited to the specific embodimentsdescribed above. All variations covered by the following claims areintended to be included in the scope of the present invention.

[0074] For instance, the intermediate layer 25 for proper growth of theGaN-based semiconductor laminate 40 on the monocrystal silicon substrate20 may be made of AlN/AlGaN instead of TiN.

1. A semiconductor light-emitting element comprising: a silicon singlecrystal substrate having a first and a second surfaces in head-tailrelationship with each other; a GaN-based semiconductor laminate formedon a selected region of the first surface with a predeterminedconductive intermediate layer interposed therebetween; a first electrodelayer having a portion in contact with an uppermost layer of theGaN-based semiconductor laminate and insulated from the monocrystalsilicon substrate; and a second electrode layer formed on a suitableportion of the monocrystal silicon substrate; wherein the monocrystalsilicon substrate is formed with a light guide for directing lightemitted from the GaN-based semiconductor laminate toward the secondsurface.
 2. The semiconductor light-emitting element according to claim1, wherein the light guide comprises a hole penetrating the monocrystalsilicon substrate thicknesswise, the GaN-based semiconductor laminateincluding a lowermost layer whose surface includes a portionsubstantially exposed to the second surface.
 3. The semiconductorlight-emitting element according to claim 2, wherein the hole is filledwith translucent resin.
 4. The semiconductor light-emitting elementaccording to claim 3, wherein the resin contains a fluorescent or lightscattering material.
 5. The semiconductor light-emitting elementaccording to claim 2, wherein the hole flares to have increasingdiameter toward the second surface.
 6. The semiconductor light-emittingelement according to claim 2, wherein the hole is parabolic to haveincreasing diameter toward the second surface.
 7. The semiconductorlight-emitting element according to claim 1, wherein the uppermost layerof the GaN-based semiconductor laminate is covered with a insulatinglayer excepting a predetermined center region contacting the firstelectrode layer.
 8. The semiconductor light-emitting element accordingto claim 7, wherein the center region has a diameter smaller than thatof the hole formed with the monocrystal silicon substrate.
 9. Thesemiconductor light-emitting element according to claim 1, wherein theselected region is provided in a depression of the first surface. 10.The semiconductor light-emitting element according to claim 9, whereinthe depression is filled with a protective member.
 11. The semiconductorlight-emitting element according to claim 10, wherein the protectivemember is heat-conductive.
 12. The semiconductor light-emitting elementaccording to claim 1, wherein the GaN-based semiconductor laminate has aportion positioned offset thicknesswise relative to the other portion.13. The semiconductor light-emitting element according to claim 1,wherein the first surface of the monocrystal silicon substrate is formedwith another electronic element.
 14. The semiconductor light-emittingelement according to claim 1, wherein the first and the second electrodelayers are arranged on the first surface side of the monocrystal siliconsubstrate.
 15. A mounting structure of a semiconductor light-emittingelement comprising: a monocrystal silicon substrate having a first and asecond surfaces in head-tail relationship with each other; a GaN-basedsemiconductor laminate formed on a selected region of the first surfacewith a predetermined conductive intermediate layer interposedtherebetween; a first electrode layer having a portion in contact withan uppermost layer of the GaN-based semiconductor laminate and insulatedfrom the monocrystal silicon substrate, the first electrode beingarranged on the first surface side of the monocrystal silicon substrate;and a second electrode layer arranged on the first surface side of themonocrystal silicon substrate; wherein the monocrystal silicon substrateis formed with a light guide for directing light emitted from theGaN-based semiconductor laminate toward the second surface, wherein themonocrystal silicon substrate is mounted on a carrier via the first andthe second electrode layers.
 16. A method of manufacturing asemiconductor light-emitting element comprising the steps of: (a)forming a GaN-based semiconductor laminate on a selected region of afirst surface of a monocrystal silicon substrate with a predeterminedconductive intermediate layer interposed therebetween, the monocrystalsilicon substrate also having a second surface in head-tail relationshipwith the first surface; (b) forming a first electrode layer and a secondelectrode layer, the first electrode layer having a portion in contactwith an uppermost layer of the GaN-based semiconductor laminate andbeing insulated from the monocrystal silicon substrate, the secondelectrode layer being formed on a suitable portion of the monocrystalsilicon substrate; and (c) forming a light guide in the monocrystalsilicon substrate for directing light emitted from the GaN-basedsemiconductor laminate toward the second surface.
 17. A semiconductorlight-emitting element comprising: a monocrystal silicon substratehaving a first and a second surfaces in head-tail relationship with eachother; and a light-emitting diode chip mounted on a selected region ofthe first surface; wherein the monocrystal silicon substrate is formedwith a light guide for directing light emitted from the light-emittingdiode chip toward the second surface.
 18. The semiconductorlight-emitting element according to claim 17, wherein the light-emittingdiode chip is a blue-color light-emitting diode chip formed by growing aGaN-based semiconductor laminate on a sapphire substrate.
 19. Thesemiconductor light-emitting element according to claim 18, wherein theblue-color light-emitting diode chip is mounted on the selected regionwith the sapphire substrate directed downward.
 20. The semiconductorlight-emitting element according to claim 18, wherein the blue-colorlight-emitting diode chip is mounted on the selected region with thesapphire substrate directed upward.
 21. The semiconductor light-emittingelement according to claim 17, wherein the light guide comprises a holepenetrating the monocrystal silicon substrate thicknesswise with aportion of the light-emitting diode chip substantially exposed to thesecond surface side.
 22. The semiconductor light-emitting elementaccording to claim 21, wherein the hole is filled with translucentresin.
 23. The semiconductor light-emitting element according to claim21, wherein the resin contains a fluorescent or light scatteringmaterial.
 24. The semiconductor light-emitting element according toclaim 17, wherein the hole flares to have increasing diameter toward thesecond surface.
 25. The semiconductor light-emitting element accordingto claim 17, wherein the hole is parabolic to have increasing diametertoward the second surface.
 26. The semiconductor light-emitting elementaccording to claim 17, wherein the selected region is provided in adepression of the first surface.
 27. The semiconductor light-emittingelement according to claim 26, wherein the depression is filled with aprotective member.
 28. The semiconductor light-emitting elementaccording to claim 17, wherein the first surface of the monocrystalsilicon substrate is formed with another electronic element.
 29. Thesemiconductor light-emitting element according to claim 17, wherein thefirst surface of the monocrystal silicon substrate is provided with afirst electrode layer connected to an electrode of the blue-colorlight-emitting diode chip, the first surface being also provided with asecond electrode layer connected to another electrode of the blue-colorlight-emitting diode chip.
 30. A mounting structure of a semiconductorlight-emitting element comprising: a monocrystal silicon substratehaving a first and a second surfaces in head-tail relationship with eachother; and a light-emitting diode chip mounted on a selected region ofthe first surface; wherein the monocrystal silicon substrate is formedwith a light guide for directing light emitted from the light-emittingdiode chip toward the second surface; the first surface of themonocrystal silicon substrate being provided with a first electrodelayer connected to an electrode of the blue-color light-emitting diodechip, the first surface being also provided with a second electrodelayer connected to another electrode of the blue-color light-emittingdiode chip, the light-emitting diode chip being mounted on a carrier viathe first and the second electrode layers.